How do I import and export documents on iPad?

There are two ways to import documents into the app. The first
way is to open them from another app like Mail or Dropbox. In those
kinds of apps you can select a file and choose to open it in
another app, and if Tabular supports that file format, it will be
listed as an option.

The other way is to import files from a computer using iTunes.
Plug your iPad into your computer, then select it in iTunes. In the
Apps tab, select Tabular in the File Sharing section. Then you can
drag and drop files into the list to have them import
automatically.

To export a document, open it from the library, then press the
wrench button at the top-left. Select the Share tab, and from there
you can choose how you want to export or share the document.